This invention relates to a flexible disk drive control method for controlling a flexible disk drive.
In the manner known in the art, the flexible disk drive (which may be called “FDD” for short) of the type is a device for carrying out data recording and reproducing operation to and from a magnetic recording medium of a flexible disk (which may be called “FD” for short) loaded therein. In addition, such a flexible disk drive is loaded in an electronic equipment such as a laptop personal computer, a notebook-size personal computer, a notebook-size word processor, or the like. The electronic equipment is called a host system.
The flexible disk drive of the type comprises magnetic heads for reading/writing data from/to the magnetic recording medium of the flexible disk, a carriage assembly for supporting the magnetic head at a tip thereof with the magnetic head movably along a predetermined radial direction to the flexible disk, a stepping motor for moving the carriage assembly along the predetermined radial direction, and a spindle motor for rotatably driving the magnetic recording medium with the flexible disk held. An operation to move the magnetic heads to a target track is called a “seek” operation in the art. This seek operation is carried out by rotating the stepping motor.
In order to control such a flexible disk drive, an FDD control apparatus is already proposed. By way of example, Japanese Unexamined Patent Publication Tokkai No. Hei 9-97,493 (97,493/1997) discloses, as the FDD control apparatus, one integrated circuit (IC) chip which incorporates first through third control circuits therein. The first control circuit is a reading/writing (hereinafter called “R/W”) control circuit for controlling reading/writing of data. The second control circuit is a stepping motor (hereinafter called “STP”) control circuit for controlling drive of the stepping motor. The third control circuit is a general controlling (hereinafter called “CTL”) control circuit for controlling whole operation of the flexible disk drive. This IC chip is generally implemented by a metal oxide semiconductor (MOS) IC chip where a number of MOS field effect transistors (FETs) are integrated therein.
The FDD control apparatus comprises not only the one IC chip but also a spindle motor IC chip for controlling drive of the spindle motor. The spindle motor IC chip is implemented by a bipolar IC chip where a number of bipolar transistors are integrated therein.
Now, flexible disk drives have different specifications due to customers or users. The specification defines, for example, drive select 0 or drive select 1, the presence or absence of a special seek function, the presence or absence of an automatic chucking function, a difference of logic for a density out signal, a difference of logic for a mode select signal, 1M mode 250 kbps or 300 kbps, and so on. If development is made of one IC chips which individually satisfy the different specification, a number types of one IC chips must be prepared. In order to avoid this, a one IC chip having a selectable function circuit is already proposed, for example, in Japanese Unexamined Patent Publication Tokkai No. Hei 9-97,839 (97,839/1997) wherein all functions satisfying all specifications are preliminarily incorporated therein and one of the functions is selected in accordance with a particular specification.
As is well known in the art, the flexible disk driven by the flexible disk drive includes a disk-shaped magnetic recording medium accessed by the magnetic head. The magnetic recording medium has a plurality of tracks on a surface thereof that serve as paths for recording data and that are formed in a concentric circle along a radial direction. The flexible disk has eighty tracks on side which include the most outer circumference track (which is named “TR00 ”) and the most inner circumference track (which is named “TR79”). The most outer circumference track TR00 is herein called the most end track.
It is necessary to position the magnetic head at a desired track position in a case where the flexible disk is accessed by the magnetic heads in the flexible disk drive. For this purpose, the carriage assembly for supporting the magnetic head at the tip thereof must be positioned. Inasmuch as the stepping motor is used as a driving arrangement for driving the carriage assembly, it is possible to easily carry out the positioning of the carriage assembly. In spite of this, it is necessary for the flexile disk drive to detect only the position of the most end track TR00 in the magnetic recording medium of the flexible disk loaded therein. In order to detect the position of the most end track TR00, the carriage assembly is provided with an interception plate which projects from a base section thereof downwards and a photointerrupter is mounted on a substrate in the vicinity of a main frame opposed to the carriage assembly. For example, see Japanese Unexamined Patent Publication Tokkai No. Hei 9-91,859 (91,859/1997). That is, it is possible to detect that the magnetic head is laid in the position of the most end track TR00 in the magnetic recoding medium of the flexible disk because the interception plate intercepts an optical path in the photointerrupter. Such a track position detecting mechanism is called a “00 sensor” in the art.
An FDD control apparatus is an apparatus for controlling the flexible disk drive. A conventional FDD control apparatus seeks the magnetic heads in a direction (for example, an inner periphery or an outer periphery) designated by an external seek direction signal when a drive select signal is put into an active state of a logic low level and when an external step signal is inputted whether or not the flexible disk is laid (inserted) in the flexible disk drive. At any rate, the conventional FDD control apparatus can carry out the seek operation in spite of insertion/noninsertion of the flexible disk.
However, in a case where the flexible disk is not inserted in the flexible disk drive, the conventional FDD control apparatus is disadvantageous in that a seek error occurs and seek noises are raised in the manner which will later be described in conjunction with FIGS. 2A and 2B.